Synthesis and Validation of Wideband Excitation Coefficients in Plane Wave Generator Systems

Plane Wave Generators (PWG) are arrays of elements arranged and excited to approximate a plane wave, creating far-field conditions within a Quiet Zone (QZ) in the near-field proximity of the array. Thanks to its compact design, the PWG offers a closer approximation to far-field conditions compared to equivalently sized Compact Antenna Test Range (CATR) systems. However, the discrete sampling by the array elements of the PWG's radiating aperture constitutes a limit to the obtainable electrical size of the QZ. As a result, PWGs are commonly used in lower-frequency measurement applications, such as UHF and VHF, where system size is a key design constraint. Consequently, PWGs often serve as a viable alternative or, more commonly, a complement to traditional CATR-based solutions, particularly for lower-frequency testing. Although PWGs have attracted significant attention in the literature, including for wideband testing, the array excitation, specifically, the selection of complex weights for the radiating elements, has typically been addressed at discrete frequencies, assuming unique excitations for each frequency. In this paper, we focus on the synthesis of excitation coefficients valid across a decade bandwidth, enabling the system to support wideband signal testing, such as when modulated signals or time-domain gating and filtering are employed. The wideband coefficients are experimentally validated on a low-frequency PWG array, demonstrating the system's capability for effective wideband measurements.